Radiator fan on 2012 JK stays in high speed


TrevorP

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Sep 12, 2021
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Decatur Tx
So I have a 2012 and after about 20min of running parked or driving a red lightning bolt icon comes on on the dash and the radiator fan goes to high speed and stays there. If you shut the keep off and restart 20min later same thing. It’s not overheating the temp stays low and I’ve changed the temp sending unit. Any ideas?
 

BLACKJKU

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Prior to this happening did you replace anything or repair anything on the Jeep? Usually when electrical problems start happening it's always good to make sure the battery clamps and cable ends are clean. Also any other grounds you can find on the Jeep.
 
OP
T

TrevorP

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Sep 12, 2021
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Location
Decatur Tx
Prior to this happening did you replace anything or repair anything on the Jeep? Usually when electrical problems start happening it's always good to make sure the battery clamps and cable ends are clean. Also any other grounds you can find on the Jeep.
Prior to this no real repairs, I’ve replaced the battery but not correlation in time between those events
 

MacGuyver

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May 13, 2020
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Wisconsin
I had this recently and it was because the radiator was a bit low, just low enough that internal pressure wouldn't get high enough to exchange coolant with the reservoir.
When the engine is cold, open the radiator cap and dump a bit in. The coolant reservoir is not the place to add. If you can't add any at all then it may be something else, but this is the easiest first check.
 

Chris

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I'm not as familiar with the JK as I am with the TJ, but is there a fan speed sensor on these things?